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We recommend the following procedure: Start with an empty mixer. Add 1 part sand. Mix in 1 part lime. Followed by 1.5 parts sand. Mix dry for at least 5 minutes. After 5 minutes slowly add water until the desired consistency is reached, it is very important not to drown the mix by adding too much water.
Do you need cement in lime mortar?
The addition of cement to lime mortars is a widespread, almost traditional practice, but few consider why it is done or the consequences. There is also confusion over the substances and chemistry involved. Typical proportions, commonly in use, are 1:1:6 (cement: non hydraulic lime: aggregate) and 1:2:9.
Can I use lime instead of cement?
Lime mortar today is primarily used in the conservation of buildings originally built using lime mortar, but may be used as an alternative to ordinary portland cement. It is made principally of lime (hydraulic, or non hydraulic), water and an aggregate such as sand.
Do you need plasticiser in lime mortar?
As you say you shouldn’t need to use a plasticiser with lime – it is more to do with the sand. Sharp sand does provide extra strength among many other benefits but the big drawback is less workability. If for whatever reason I’m using sharp sand – i tend to cheat a little and add some soft sand to the mix.
Why is lime plaster no longer commonly used?
The promotion of modern gypsum-based plasters has led to the almost complete demise of lime plastering, and of many of the traditional skills associated with the craft. This has been exacerbated by the plastering trade being divided into flat and decorative work, with new ‘fibrous plasterwork’ being made in workshops.
Is lime mortar better than cement?
Lime mortar has better properties than straight concrete mortar. These qualities help structures withstand weathering and aging better than before. If your stonework has an ordinary concrete mortar between the stones, you will have probably noticed cracking, pitting and crumbling.
What is the ratio of sand to lime for mortar?
Mortars and grouts Cement lime mortar may be made at ratios of 1:0.25:3 (cement:lime:sand) for higher strength and durability down to 1:3:12 for a weaker mix capable of accommodating more movement. Cement lime mortar should not normally be used below the damp proof course (dpc).
How do you make mortar without cement?
Here’s a bit of a starter for making muddy mortar. Mix the earth, clay, water and straw together. Stomp it or churn it well. Leave the mixture to percolate for a week. Add sand to this mixture (and lime if needed). Shovel ingredients onto an old sheet of plastic and stomp stomp stomp.
Can I use Washing up liquid instead of plasticiser?
“Washing up liquid affects the long term structural integrity of mortar and should never be used as a substitute for plasticiser.”Nov 30, 2007.
What is the best mix for lime mortar?
A conventional cement mixer can be used although for larger projects a paddle mixer is preferable. The mix is typically 1 part lime : 2.5 parts sand.
Can I use plasticiser instead of lime in Render?
Plasticiser can be used instead of lime to improve the workability and durability of mortar mixes. Lime tends to delay the drying time of mortar, whereas plasticisers don’t, still allowing ample time for adjustments. Ideal for use in bricklaying, pointing, rendering and back coatings.
Can you mix lime with cement?
Incorporating an appropriate proportion of hydrated lime into a cement-based mixture improves plasticity and workability, making the product easier to handle on the trowel. Hydrated lime also increases water retention which helps to improve the contact and bond with the substrate.
Should I use lime mortar for pointing?
Lime mortar is advantageous as it allows the structure to breathe, because of this moisture wont get trapped within a building causing a number of issues such as damp walls. Where your inspection uncovers any defects in pointing, the correct quantity should be removed.
Why is my lime mortar crumbling?
Failing mortar can usually be attributed to a lack of carbonation of the lime within the mortar meaning that the mortar will have little if any, strength. It can also be caused by the mortar drying too fast by either not wetting the background or lack of tending and protection afterwards.
Does lime mortar stop damp?
A stone or tile floor laid on earth or a lime mortar will allow any residual ground moisture to escape and evaporate. One of the biggest causes of damp issues in old houses is when the fabric is “blocked” from breathing by the use of modern impervious materials.
Can I paint lime plaster?
Lime plaster can be painted with our natural emulsion paint. In contrast to clay paint, natural emulsion has a more opaque surface, which makes it more durable and more effective.
Does lime weaken mortar?
The use of lime in mortar reduces the compressive and flexural strength of the hardened mortar.
Is lime mortar expensive?
Lime products are considerably more expensive to buy than a cement render and the mix ratio of aggregate to lime is approximately 3 times greater than that of cement and gypsum.
What’s the difference between hydraulic lime and hydrated lime?
The more hydraulic a lime is the faster it sets and the higher it’s final strength, but this means that it is less breathable and flexible. NHL5 is the most hydraulic, then NHL3. Hydrated lime simply means that a controlled amount of water is added to quicklime to make a powder that is more stable and safe to handle.
What is the best mortar mix for pointing?
Mortar Mix for Pointing The preferable mortar mix ratio for pointing is 1-part mortar and either 4 or 5 parts building sand. The ratio will vary depending on what exactly is being pointed. For bricklaying, you will usually want a 1:4 ratio with plasticiser added to the mixture.
